This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-190547, filed Jun. 26, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a semiconductor resin mold and a semiconductor resin molding method using the mold, particularly to a resin mold for use in molding a semiconductor chip mounted on a resin tape substrate having a circuit wiring with a resin on the resin tape substrate and a semiconductor resin molding method using the mold.
In recent years, with size and cost reduction of an electronic apparatus, a resin molded semiconductor device for use in the electronic apparatus is requested to be thin and dense, and productivity enhancement and cost reduction are further required. Instead of the usual semiconductor device constituted by molding a semiconductor chip mounted on a lead frame with a resin, a BGA resin molded semiconductor device of a resin tape type has been developed by mounting a plurality of semiconductor chips on a resin tape substrate having a circuit wiring, molding the semiconductor chip with the resin on the resin tape substrate, disposing a metal ball electrode on a back surface of the resin tape substrate, and cutting/separating the substrate into semiconductor chip units.
A resin molding method of the latter semiconductor device will be described hereinafter.
First, the resin tape substrate with a plurality of semiconductor chips mounted thereon is prepared, and a mold constituted of upper and lower mold members is prepared. Each semiconductor chip is fixed onto a chip mounting surface of the resin tape substrate via an adhesive layer, and connected to the circuit wiring formed on the resin tape substrate via a bonding wire.
Subsequently, the resin tape substrate is disposed between the upper and lower mold members of the resin mold. In this case, respective semiconductor chip mount portions are disposed in a plurality of cavities formed by the upper and lower mold members, and the back surface of the resin tape substrate is closely attached to an attachment area surface of a bottom surface of the cavity.
Subsequently, a resin tablet is introduced into a pot disposed to the mold, heated and molten. The molten resin is pressurized by a plunger of a transfer mold apparatus, and supplied into the cavity from the pot through a runner and inflow gate. Thereby, the respective semiconductor chips are altogether molded by the resin on the mount portion of the resin tape substrate, and a resin molded body with the back surface of the resin tape substrate exposed therefrom is formed.
Subsequently, the respective metal ball electrodes are disposed on an external electrode of the circuit wiring exposed to the back surface of the resin tape substrate, and the resin tape substrate is diced to separate individual resin molded semiconductor devices.
As described above, in the resin molding process of the resin molded semiconductor devices using the resin tape substrate, in order to expose the back surface of the resin tape substrate from the molding resin, the back surface of the resin tape substrate needs to be attached fixedly to the attachment area surface of the bottom surface in the cavity of the mold.
Here, since a tape material of the resin tape substrate, adhesive layer for fixing the semiconductor chip, solder resist for protecting and covering the circuit wiring, semiconductor chip, and circuit wiring material are formed of different materials, the materials are different from one another in thermal expansion coefficient. When the materials are heated, for example, at 180xc2x0 C. during molding, the resin tape substrate warps toward the semiconductor chip because of the difference of the thermal expansion coefficient. Therefore, the resin tape substrate floats above the attachment area surface of the bottom surface of the cavity, and the molten resin charged into the cavity disadvantageously enters to a space between the back surface of the resin tape substrate and the cavity surface.
Since the back surface of the resin tape substrate is covered with the resin entered into the space between the back surface of the resin tape substrate and the cavity surface in this manner, a molding defect occurs in the resin molded body.
Also on the side of the semiconductor chip attached to the upper surface of the resin tape substrate, since the substrate is curved in the cavity, a part of the resin tape substrate disadvantageously contacts, for example, a cavity ceiling portion. Therefore, a portion insufficiently filled with the resin is generated, and the molding defect occurs in the resin molded body. Therefore, a yield of the resin molded semiconductor device is lowered, and productivity is remarkably deteriorated.
According to a first aspect of the present invention, there is provided a semiconductor resin mold comprising:
a resin molding cavity having an attachment surface to which a resin tape substrate with a semiconductor chip mounted thereon is attached; and
a plurality of suction holes opened in the attachment surface and connectable to a suction system.
According to the first aspect of the present invention, the resin tape substrate with the semiconductor chip mounted thereon is firmly attached onto the attachment area surface of the bottom surface of the cavity by the suction holes opened in the attachment area surface of the bottom surface of the cavity formed in the mold and connected to the suction system. Therefore, the resin tape substrate can be prevented from warping by heating during resin molding, and the molten resin supplied in the cavity can be prevented from disadvantageously entering to the back surface of the resin tape substrate.
According to a second aspect of the present invention, there is provided a semiconductor resin molding method of sealing a semiconductor chip mounted on a resin tape substrate with a resin molded body excluding a back surface of the resin tape substrate. The method comprising:
preparing a mold comprising a cavity having a plurality of suction holes connectable to a suction system in an attachment surface to which the resin tape substrate is attached;
attaching the resin tape substrate to the attachment surface of the cavity of the mold;
sucking/fixing the resin tape substrate to the attachment surface of the cavity after the step of attaching the resin tape substrate to the attachment surface; and
supplying a resin into the cavity of the mold after the step of sucking/fixing the resin tape substrate onto the attachment surface.
According to the second aspect of the present invention, the resin tape substrate with the semiconductor chip mounted thereon is attached to the attachment area surface of the bottom surface of the cavity. After the resin tape substrate is firmly attracted onto the attachment area surface of the cavity bottom surface by the suction holes opened in the attachment area surface of the bottom surface of the cavity, the resin molding is performed. Therefore, the resin tape substrate can be prevented from warping by heating during resin molding, and the molten resin supplied in the cavity is prevented from entering to the back surface of the resin tape substrate. This can avoid occurrence of a molding defect of the resin molded body with the resin tape substrate back surface exposed therefrom, and can also prevent the occurrence of a resin uncharged portion on the side of the semiconductor chip on the upper surface of the resin tape substrate. Therefore, the productivity of the resin molded semiconductor device can remarkably be enhanced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.